Studies on extraction of phosphorus from phosphate ore by electric furnace with different fluxing agents

The extraction of phosphorus from phosphate ore using various fluxing agents (i.e. silicon dioxide, silica and potassium feldspar) was studied. To optimize the phosphate rock reduction process, different reaction time, temperature and acidity value for different fluxing agents were investigated. The highest amount of extracted phosphorus was obtained at 1300 °C, with a reaction time of 40 min, and acidity value of 0.85. Using silicon dioxide, silica or potassium feldspar as fluxing agents, the obtained phosphorus conversion rates were 95.00%, 96.76% and 99.61%, respectively. In addition, the reduction kinetics of phosphate ore, prepared with various fluxing agents, was characterized via thermogravimetric analysis. The results showed that the activation energy of the reaction using potassium feldspar as a fluxing agent was lower than that of the traditional process with silica and silicon dioxide. Therefore, higher extraction of phosphorus and energy conservation can be achieved by using potassium feldspar as fluxing agent, instead of silica, in a phosphorus furnace. Finally, the mechanism of every fluxing agent in the extraction of phosphorus was further investigated by X-ray diffraction and scanning electron microscopy.